1. Field of the Invention
The present invention relates to a disposable indwelling catheter placement unit for insertion of a catheter into a blood vessel; and more particularly relates to a unit for indwelling a lengthy catheter into the blood vessel in the vicinity of the heart of a patient up to a desired depth therein and in a sterile manner.
2. Description of Relevant Art
Various improvements have hitherto been attempted to place a catheter made of a plastic tube into the blood vessel of a patient by inserting a tubular needle for the purpose of introducing the catheter as, for example, disclosed in published Japanese Patent Application 20023/1981. However, problems persist when attempting to indwell a desired length of a lengthy catheter into a blood vessel while maintaining sterile conditions.
After the placement of a catheter into the blood vessel with a conventional placement unit, it is impossible to remove the front portion of an insertion means and a cannulated needle from the catheter thus inserted. Accordingly, it is necessary to draw blood-stained insertion means and cannulated needle toward the hands of the medical user so as to fit the same to parts of a base of the catheter, which if viewed by the patient, inevitably makes the patient anxious and uncomfortable.
The above-mentioned insertion means of a conventional placement unit is constituted in a stainless tube, which is formed by insertion molding, a molding operation that is troublesome. Furthermore, a tubular sheath of the introducer unit is made of hard polyethylene, and as a result, there is danger that the sliding portion of the hard sheath tube will be worn away and produce fine powders which could eaily enter the body after having been stuck to the catheter. Therefore, the insertion means of the conventional unit should be made of a fine metal in order to slide smoothly on the sheath tube by reducing sliding resistance. The sliding resistance is an important factor to be considered, when inserting the catheter within the sheath tube, because the resistance between the front portion of the catheter and the blood vessel can only be sensed indirectly in an actual operation. Accordingly, the likelihood of the catheter being forced into the blood vessel and piercing the wall of the vessel is substantial, especially when the sliding resitance of the catheter in the sheath tube and insertion means is large enough to mask the sliding resistance of the catheter within the blood vessel. Such an accident as the above has frequently occurred unexpectedly.
With the conventional placement unit, it is difficult to confirm the length of the catheter inserted into the blood vessel directly through the insertion means because the conventional sheath tube is semi-transparent and the conventional insertion means is not transparent.
Because the hard tubular parts and blood-stained plastic needle of a conventional placement unit remain on the cathether as described above, they are a hindrance when fixing the catheter onto the skin. Furthermore, because in a conventional placement unit, the catheter and capillary extension tube extending from the catheter end outside the patient for connection of the catheter to a tubing connector following catheter placement are integrally constituted, repeated substitutions of a new adaptor for the adaptor already connected to the extension tube, such as for sterilization of the adaptor, may cause such troubles, such as looseness of an arrangement of the catheter, or cracks in the catheter end.
The length of a conventional catheter extending outside the body depends upon the extent to which the catheter is inserted into the blood vessel. Accordingly, it is often necessary to form the excess catheter into a loop.
In carrying out the insertion of the catheter into the blood vessel by means of a film or bag method, two kinds of manual operation are required: hauling in, and pulling back.